ECHINOSOMA TENUE. 165 



most abundant near the ambitus, though they may occur far up on the 

 abactinal surface. The calcareous particles in the tube-feet are small and 

 not very abundant, irregular, perforated plates. 



Echinosoma tenue Pomel. 



Fhormosoma tenuis A. Agassiz, 1879. Proc. Am. Acad., XIV, p. 202. 

 Phormosoma tenue A. Agassiz, 1881. "Challenger" Ech., p. 91; Pis. XIII, XIV, et al. 

 Echinosoma tenue Pomel, 1883. Class. Meth. Ech., p. 108. 



Pacific Ocean; 1875-2750 fathoms. 



Plate 67, figs. 12-21. 



The specimens before us, collected by the " Albatross," show that unless 

 there is some mistake in the labels, this species has an astonishing bathy- 

 metrical range. We have compared most carefully the specimens from 

 Stations 3784, 4928 and 5084 with one of the co-types of tenue from " Chal- 

 lenger" Station 237, and we find they agree so perfectly in all details that it 

 is impossible to doubt their identity. The specimen from 3707, on the other 

 hand, is small (about 30 mm. h. d.) and more or less damaged, and the origi- 

 nal label has the station number so faint that it has been repeated in lead 

 pencil, and in this repetition there is chance for error ; Stations 3710, 3711, 

 3712, and 3736 were the only Japanese stations occupied by the " Alba- 

 tross " in 1900 where this species would be expected to occur. This small 

 specimen has the tube-feet arranged as in tenue, so far as they can be made 

 out, and the pedicellarige, so far as may be judged from a very few exam- 

 ples, are like those of tenue. We therefore believe that the identification 

 of the specimen is correct, but we do not believe it was taken at Station 

 3707. The color of the specimens before us is varied; the "Challenger" 

 specimen is yellowish, with strong indications of violet actinally, and has 

 light-colored tube-feet ; one of the specimens from 3784 is also somewhat 

 yellowish, especially abactinally, but the tube-feet are dark violet in strik- 

 ing contrast ; the other specimens range from light to dark violet without 

 a trace of yellow on the test, but in some cases the tube-feet are brownish- 

 yellow. The color of both test and feet seems to depend on the extent 

 to which the bright violet pigment is developed. 



The arrangement of the tube-feet, abactinally, in tenue, is characteristic 

 when well marked, but there is some individual diversity. In the " Chal- 

 lenger " specimen there are two series closely approximated to each other, 

 on each side of the ambulacrum ; in the outer series there are practically 



